Multifrequency variability of the blazar AO 0235+164 the WEBT campaign in 2004-2005 and long-term SED analysis

Autores
Romero, Gustavo Esteban; Araudo, Anabella Teresa; Cellone, Sergio Aldo
Año de publicación
2006
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Aims. A huge multiwavelength campaign targeting the blazar AO 0235+164 was organized by the Whole Earth Blazar Telescope (WEBT) in 2003-2005 to study the variability properties of the source. Methods. Monitoring observations were carried out at cm and mm wavelengths, and in the near-IR and optical bands, while three pointings by the XMM-Newton satellite provided information on the X-ray and UV emission. Results. We present the data acquired during the second observing season, 2004-2005, by 27 radio-to-optical telescopes. The ∼2600 data points collected allow us to trace the low-energy behaviour of the source in detail, revealing an increased near-IR and optical activity with respect to the previous season. Increased variability is also found at the higher radio frequencies, down to ∼15 GHz, but not at the lower ones. While the X-ray (and optical) light curves obtained during the XMM-Newton pointings reveal no significant short-term variability, the simultaneous intraday radio observations with the 100 m telescope at Effelsberg show flux-density changes at 10.5 GHz, which are more likely due to a combination of intrinsic and extrinsic processes. Conclusions. The radio (and optical) outburst predicted to peak around February-March 2004 on the basis of the previously observed 5-6 yr quasi-periodicity did not occur. The analysis of the optical light curves reveals now a longer characteristic time scale of variability of ∼8 yr, which is also present in the radio data. The spectral energy distributions corresponding to the XMM-Newton observations performed during the WEBT campaign are compared with those pertaining to previous pointings of X-ray satellites. Bright, soft X-ray spectra can be described in terms of an extra component, which appears also when the source is faint through a hard UV spectrum and a curvature of the X-ray spectrum. Finally, there might be a correlation between the X-ray and optical bright states with a long time delay of about 5 yr, which would require a geometrical interpretation.
La lista completa de autores que integran el documento puede consultarse en el archivo.
Facultad de Ciencias Astronómicas y Geofísicas
Materia
Ciencias Astronómicas
Ciencias Exactas
Galaxies: active
Galaxies: BL lacertae objects: general
Galaxies: BL lacertae objects: individual: AO 0235+164
Galaxies: jets
Galaxies: quasars: general
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/83062

id SEDICI_a1f155a600d7405cac70ce8dd98db434
oai_identifier_str oai:sedici.unlp.edu.ar:10915/83062
network_acronym_str SEDICI
repository_id_str 1329
network_name_str SEDICI (UNLP)
spelling Multifrequency variability of the blazar AO 0235+164 the WEBT campaign in 2004-2005 and long-term SED analysisRomero, Gustavo EstebanAraudo, Anabella TeresaCellone, Sergio AldoCiencias AstronómicasCiencias ExactasGalaxies: activeGalaxies: BL lacertae objects: generalGalaxies: BL lacertae objects: individual: AO 0235+164Galaxies: jetsGalaxies: quasars: general<b>Aims.</b> A huge multiwavelength campaign targeting the blazar AO 0235+164 was organized by the Whole Earth Blazar Telescope (WEBT) in 2003-2005 to study the variability properties of the source. <b>Methods.</b> Monitoring observations were carried out at cm and mm wavelengths, and in the near-IR and optical bands, while three pointings by the XMM-Newton satellite provided information on the X-ray and UV emission. <b>Results.</b> We present the data acquired during the second observing season, 2004-2005, by 27 radio-to-optical telescopes. The ∼2600 data points collected allow us to trace the low-energy behaviour of the source in detail, revealing an increased near-IR and optical activity with respect to the previous season. Increased variability is also found at the higher radio frequencies, down to ∼15 GHz, but not at the lower ones. While the X-ray (and optical) light curves obtained during the XMM-Newton pointings reveal no significant short-term variability, the simultaneous intraday radio observations with the 100 m telescope at Effelsberg show flux-density changes at 10.5 GHz, which are more likely due to a combination of intrinsic and extrinsic processes. <b>Conclusions.</b> The radio (and optical) outburst predicted to peak around February-March 2004 on the basis of the previously observed 5-6 yr quasi-periodicity did not occur. The analysis of the optical light curves reveals now a longer characteristic time scale of variability of ∼8 yr, which is also present in the radio data. The spectral energy distributions corresponding to the XMM-Newton observations performed during the WEBT campaign are compared with those pertaining to previous pointings of X-ray satellites. Bright, soft X-ray spectra can be described in terms of an extra component, which appears also when the source is faint through a hard UV spectrum and a curvature of the X-ray spectrum. Finally, there might be a correlation between the X-ray and optical bright states with a long time delay of about 5 yr, which would require a geometrical interpretation.La lista completa de autores que integran el documento puede consultarse en el archivo.Facultad de Ciencias Astronómicas y Geofísicas2006-08-31info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdf731-743http://sedici.unlp.edu.ar/handle/10915/83062enginfo:eu-repo/semantics/altIdentifier/issn/0004-6361info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361:20065744info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International (CC BY 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-09-29T11:15:45Zoai:sedici.unlp.edu.ar:10915/83062Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-29 11:15:45.971SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Multifrequency variability of the blazar AO 0235+164 the WEBT campaign in 2004-2005 and long-term SED analysis
title Multifrequency variability of the blazar AO 0235+164 the WEBT campaign in 2004-2005 and long-term SED analysis
spellingShingle Multifrequency variability of the blazar AO 0235+164 the WEBT campaign in 2004-2005 and long-term SED analysis
Romero, Gustavo Esteban
Ciencias Astronómicas
Ciencias Exactas
Galaxies: active
Galaxies: BL lacertae objects: general
Galaxies: BL lacertae objects: individual: AO 0235+164
Galaxies: jets
Galaxies: quasars: general
title_short Multifrequency variability of the blazar AO 0235+164 the WEBT campaign in 2004-2005 and long-term SED analysis
title_full Multifrequency variability of the blazar AO 0235+164 the WEBT campaign in 2004-2005 and long-term SED analysis
title_fullStr Multifrequency variability of the blazar AO 0235+164 the WEBT campaign in 2004-2005 and long-term SED analysis
title_full_unstemmed Multifrequency variability of the blazar AO 0235+164 the WEBT campaign in 2004-2005 and long-term SED analysis
title_sort Multifrequency variability of the blazar AO 0235+164 the WEBT campaign in 2004-2005 and long-term SED analysis
dc.creator.none.fl_str_mv Romero, Gustavo Esteban
Araudo, Anabella Teresa
Cellone, Sergio Aldo
author Romero, Gustavo Esteban
author_facet Romero, Gustavo Esteban
Araudo, Anabella Teresa
Cellone, Sergio Aldo
author_role author
author2 Araudo, Anabella Teresa
Cellone, Sergio Aldo
author2_role author
author
dc.subject.none.fl_str_mv Ciencias Astronómicas
Ciencias Exactas
Galaxies: active
Galaxies: BL lacertae objects: general
Galaxies: BL lacertae objects: individual: AO 0235+164
Galaxies: jets
Galaxies: quasars: general
topic Ciencias Astronómicas
Ciencias Exactas
Galaxies: active
Galaxies: BL lacertae objects: general
Galaxies: BL lacertae objects: individual: AO 0235+164
Galaxies: jets
Galaxies: quasars: general
dc.description.none.fl_txt_mv <b>Aims.</b> A huge multiwavelength campaign targeting the blazar AO 0235+164 was organized by the Whole Earth Blazar Telescope (WEBT) in 2003-2005 to study the variability properties of the source. <b>Methods.</b> Monitoring observations were carried out at cm and mm wavelengths, and in the near-IR and optical bands, while three pointings by the XMM-Newton satellite provided information on the X-ray and UV emission. <b>Results.</b> We present the data acquired during the second observing season, 2004-2005, by 27 radio-to-optical telescopes. The ∼2600 data points collected allow us to trace the low-energy behaviour of the source in detail, revealing an increased near-IR and optical activity with respect to the previous season. Increased variability is also found at the higher radio frequencies, down to ∼15 GHz, but not at the lower ones. While the X-ray (and optical) light curves obtained during the XMM-Newton pointings reveal no significant short-term variability, the simultaneous intraday radio observations with the 100 m telescope at Effelsberg show flux-density changes at 10.5 GHz, which are more likely due to a combination of intrinsic and extrinsic processes. <b>Conclusions.</b> The radio (and optical) outburst predicted to peak around February-March 2004 on the basis of the previously observed 5-6 yr quasi-periodicity did not occur. The analysis of the optical light curves reveals now a longer characteristic time scale of variability of ∼8 yr, which is also present in the radio data. The spectral energy distributions corresponding to the XMM-Newton observations performed during the WEBT campaign are compared with those pertaining to previous pointings of X-ray satellites. Bright, soft X-ray spectra can be described in terms of an extra component, which appears also when the source is faint through a hard UV spectrum and a curvature of the X-ray spectrum. Finally, there might be a correlation between the X-ray and optical bright states with a long time delay of about 5 yr, which would require a geometrical interpretation.
La lista completa de autores que integran el documento puede consultarse en el archivo.
Facultad de Ciencias Astronómicas y Geofísicas
description <b>Aims.</b> A huge multiwavelength campaign targeting the blazar AO 0235+164 was organized by the Whole Earth Blazar Telescope (WEBT) in 2003-2005 to study the variability properties of the source. <b>Methods.</b> Monitoring observations were carried out at cm and mm wavelengths, and in the near-IR and optical bands, while three pointings by the XMM-Newton satellite provided information on the X-ray and UV emission. <b>Results.</b> We present the data acquired during the second observing season, 2004-2005, by 27 radio-to-optical telescopes. The ∼2600 data points collected allow us to trace the low-energy behaviour of the source in detail, revealing an increased near-IR and optical activity with respect to the previous season. Increased variability is also found at the higher radio frequencies, down to ∼15 GHz, but not at the lower ones. While the X-ray (and optical) light curves obtained during the XMM-Newton pointings reveal no significant short-term variability, the simultaneous intraday radio observations with the 100 m telescope at Effelsberg show flux-density changes at 10.5 GHz, which are more likely due to a combination of intrinsic and extrinsic processes. <b>Conclusions.</b> The radio (and optical) outburst predicted to peak around February-March 2004 on the basis of the previously observed 5-6 yr quasi-periodicity did not occur. The analysis of the optical light curves reveals now a longer characteristic time scale of variability of ∼8 yr, which is also present in the radio data. The spectral energy distributions corresponding to the XMM-Newton observations performed during the WEBT campaign are compared with those pertaining to previous pointings of X-ray satellites. Bright, soft X-ray spectra can be described in terms of an extra component, which appears also when the source is faint through a hard UV spectrum and a curvature of the X-ray spectrum. Finally, there might be a correlation between the X-ray and optical bright states with a long time delay of about 5 yr, which would require a geometrical interpretation.
publishDate 2006
dc.date.none.fl_str_mv 2006-08-31
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
Articulo
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://sedici.unlp.edu.ar/handle/10915/83062
url http://sedici.unlp.edu.ar/handle/10915/83062
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/issn/0004-6361
info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361:20065744
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International (CC BY 4.0)
eu_rights_str_mv openAccess
rights_invalid_str_mv http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International (CC BY 4.0)
dc.format.none.fl_str_mv application/pdf
731-743
dc.source.none.fl_str_mv reponame:SEDICI (UNLP)
instname:Universidad Nacional de La Plata
instacron:UNLP
reponame_str SEDICI (UNLP)
collection SEDICI (UNLP)
instname_str Universidad Nacional de La Plata
instacron_str UNLP
institution UNLP
repository.name.fl_str_mv SEDICI (UNLP) - Universidad Nacional de La Plata
repository.mail.fl_str_mv alira@sedici.unlp.edu.ar
_version_ 1844616029714513920
score 13.070432